Try monitoring the browser thread state using VBScript. Here's an example directly from MSDN:
Set objDictionary = CreateObject("Scripting.Dictionary")
strComputer = "."
Set objWMIService = GetObject("winmgmts:{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2")
Set colProcesses = objWMIService.ExecQuery("SELECT * FROM Win32_Process")
For Each objProcess in colProcesses
objDictionary.Add objProcess.ProcessID, objProcess.Name
Next
Set colThreads = objWMIService.ExecQuery("SELECT * FROM Win32_Thread")
For Each objThread in colThreads
intProcessID = CInt(objThread.ProcessHandle)
strProcessName = objDictionary.Item(intProcessID)
Wscript.Echo strProcessName & VbTab & objThread.ProcessHandle & VbTab & objThread.Handle & VbTab & objThread.ThreadState
Next